JPH11198189A - Injection molding equipment equipped with inter-manifold melt transfer bushing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding equipment for multilaminarly-molding two materials, the pouring temperatures of which are different from each other by a method wherein a heat insulating space is equipped between a front and a rear distributing manifolds for melt to be heated. SOLUTION: Each nozzle to be heated 10 extending from a front side manifold 18 has a center melt channel 56 and respective annular melt channels 62 and 64 extending the periphery of this center melt channel. Each melt transfer bushing 96 has a center melt bore, which extends by crossing an air space 84 so as to carry a melt from a rear side manifold to one of the melt channels 62 and 64 of each nozzle to be heated 10. The melt transfer bushing 96 has a head part, which provides a spacer between two manifolds, and a long and narrow stem portion extending to one of the nozzles to be heated through the bore passing through the front side manifold. An air space 124 round the stem portion thermally separates the melt sent from the rear side manifold from the high temperature front side manifold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates generally to multi-layer injection molding equipment and, more particularly, to a rear melt distribution manifold that extends from a rear melt distribution manifold across a front melt distribution manifold across an insulated air space. Apparatus with a melt transfer bush extending to

[0002]

2. Description of the Prior Art Injection molding equipment for producing multi-layer protective containers for food or preforms or parisons for beverage bottles is well known. Often, the inner and outer layers are made of a polyethylene terephthalate (PET) type material, and one or more barrier layers are made of a material such as ethylene vinyl alcohol copolymer (EVOH) or nylon. In some multi-cavity devices, two different melts are
Dispensed through a single melt distribution manifold with different passages. However, preferably, the injection temperature is about 565 ° F (206.1 ° C) and 204.4 ° C, respectively.
For materials different than (400 ° F.), the two melts are dispensed through two different melt distribution manifolds. In some cases, two melts are injected sequentially, and in other cases, both co-injection and sequential injection are used. The two materials are injected through heated nozzles each having a central melt channel and one or more annular melt channels extending around the central melt channel to a gate following the cavity.

As shown in US Pat. No. 5,223,275 issued to Gelato on June 29, 1993,
It is known to separate the front and rear melt distribution manifolds by an insulated air space and to flow the melt from the rear melt distribution manifold through a flat spacer washer mounted between the two manifolds. I have. While suitable for some applications, this has the disadvantage that there is not enough thermal separation between the front melt distribution manifold and the melt flowing from the rear melt distribution manifold through the front melt distribution manifold. is there.

[0004]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a multi-layer injection molding apparatus having a melt transfer bush that extends forward from a rear melt distribution manifold into a bore extending through a front melt distribution manifold. The provision is to at least partially overcome the disadvantages of the prior art.

[0005]

SUMMARY OF THE INVENTION To this end, the present invention provides, in one of its aspects, a front melt attached to a mold that extends substantially parallel to one another with an insulated air space therebetween. Provided is a multi-cavity hot runner injection molding apparatus for multi-layer molding, having a distribution manifold and a rear melt distribution manifold. It has a number of heated nozzles each having a rear end, a front end, and a central melt channel penetrating from the rear end to the front end. Each heated nozzle has an inner annular melt channel extending around a central melt channel to a front end, the melt bore extending from a rear end of the heated nozzle to the inner annular melt channel. . Each heated nozzle is an outer annular melt channel extending around the central melt channel and the inner annular melt channel to a forward end, wherein one or more melt bores are formed in an outer annular shape from a rear end of the heated nozzle. There is also an outer annular melt channel extending to the melt channel. The heated nozzles are attached to the mold with the rear end of each heated nozzle abutting the front melt distribution manifold. The first from the first melt source
A melt passage branching within the front melt distribution manifold, splitting again, a central melt channel, and one or more melt bores extending from the rear end of the heated nozzle to the outer annular melt channel; It extends through the outer annular melt channel of each heated nozzle to a gate adjacent to the front end of the heated nozzle following the mold cavity. A second melt passage from the second melt source branches in the rear melt distribution manifold and extends through the first melt bore and the inner annular melt channel of each heated nozzle to the gate. A plurality of melt transfer bushes are provided, each having a rear end, a front end, and a central melt bore penetrating from the rear end to the front end. Each melt transfer bush is mounted in position, from the rear melt distribution manifold, across the adiabatic air space between the rear melt distribution manifold and the front melt distribution manifold, one heated nozzle Extending through the front melt distribution manifold to a first melt bore extending from the rear end to the inner annular melt channel. Thus, the central bore through each melt transfer bush forms part of the second melt passage.

In another aspect, the present invention further provides a front melt distribution manifold and a rear melt distribution manifold attached to a mold that extend substantially parallel to each other with an insulated air space therebetween. The present invention provides a multi-cavity hot runner injection molding device for multilayer molding. It has a number of heated nozzles each having a central melt channel extending therethrough from a rear end, a front end, and a rear end to a front end. Each heated nozzle is an annular melt channel extending around a central melt channel to a front end, with one or more melt bores extending from the rear end of the heated nozzle to the annular melt channel. Has body channels. The heated nozzles are attached to the mold with the rear end of each heated nozzle abutting the front melt distribution manifold. A first melt passage from the first melt source branches in the front melt distribution manifold and passes through one or more melt bores and an annular melt channel of each heated nozzle to form a mold. It extends to the gate adjacent to the front end of the heated nozzle following the cavity. A second melt passage from the second melt source branches in the rear melt distribution manifold and extends through the central melt channel of each heated nozzle to the gate. A number of melt transfer bushes are provided, each melt transfer bush having a head portion provided at a rear end, an elongated stem portion extending forward from the head portion to a front end, and a center penetrating from the rear end to the front end. Has a bore. Each melt transfer bush is mounted in alignment with the central melt channel of one heated nozzle. The head portion extends between the rear melt distribution manifold and the front melt distribution manifold as a spacer that forms an adiabatic air space between the manifolds. An elongated stem portion extends forward from the head portion and into a bore through the front melt distribution manifold, in alignment with the central melt channel through the aligned heated nozzle. Thus, a central bore extending through each melt transfer bush receives an elongate pin extending forwardly from the bore into a central melt channel in the aligned heated nozzle, and a second melt from a second melt source. A passage extends along the elongate pin.

[0007] Other objects and advantages of the present invention will become more apparent by reading the following description with reference to the accompanying drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. This figure shows a portion of a multi-cavity sprue gate injection molding apparatus for molding three-layer preforms or other products by coinjection molding. A number of heated nozzles 10 are mounted on a mold 12 and the rear ends 14 of these nozzles abut a front surface 16 of a steel melt distribution manifold 18. The number of plates in the mold can be increased depending on the application, but in this case, bolts 26
Nozzle retainer plate 20, manifold retainer plate 22, back plate 24, and cavity retainer plate 28 secured to each other by
Is shown. The front end 30 of each heated nozzle 10 is aligned with a gate 32 that extends through a cooled gate insert 34 to a cavity 36. This cavity 36 for producing a beverage bottle preform is provided with a cavity insert 38
And the mold core 40 in a conventional manner.

Each heated nozzle 10 is heated by an integral electric heating element 42 having terminals 44. Each heated nozzle 10 seats in an opening 46 of the nozzle retainer plate 20 with a rear collar portion 48 of each heated nozzle 10 received in a circular positioning seat 50 extending around the opening 46. doing. This allows
An insulated air space 52 is formed between the heated nozzle 10 and the molding die 12 surrounding the nozzle. Cooling of the mold 12 is performed by pumping cooling water through a cooling conduit 54. Each heated nozzle 10 has a melt channel 56 extending from its rear end 14 to its front end 30. Each heated nozzle 10 has an insert portion 58 consisting of several parts 60. These parts fit together and extend around the central melt channel 56 to the front end 30 and an inner annular melt channel 62 and a front end 30 around the inner annular melt channel 62 and the central melt channel 56.
And an outer annular melt channel 64 extending therefrom. In this configuration, heated nozzle 10 extends from rear end 14 and has a single melt bore 66 connected to inner annular melt channel 67, and extends from rear end 14 of heated nozzle 10 to outer annular melt channel 64. It has four spaced apart melt bores 68.

The front melt distribution manifold 18 is heated by an integral electric heating element 70. The manifold 18 includes the manifold 1 and the surrounding cooled mold 1.
2 and a screw 7 extending into each heated nozzle 10 such that an adiabatic air space 76 extends between the two.
4. A rear melt distribution manifold 78 made of steel is attached to the mold 12 extending parallel to the front manifold 18 by a number of resilient insulating spacers 80 extending between the manifold and the back plate 24. As can be seen, the front manifold 18 and the rear manifold 78 are separated by a spacer 82 so as to form an adiabatic air space 84 therebetween. As will be described in more detail below, the rear melt distribution manifold 78 is heated by an integral electrical heating element 86 to a lower operating temperature than the front melt distribution manifold 18 and provides an insulated air space 84 between these manifolds. Provide sufficient thermal separation to maintain this temperature difference.

A first melt passage 88 extends from the central inlet 90 through a cylindrical manifold extension 92 and branches within the front melt distribution manifold 18, these passages being aligned with each heated nozzle 10. And extends through a melt split bush 94 seated on the front face 16 of the front melt distribution manifold 18. Melt distribution bush 94
Discloses a currently pending Canadian patent application No. 2,219, entitled "Injection Molding Apparatus with Melt Split Bush".
As described in EP 054, it is made of three layers of steel brazed together. By reference to this patent, the disclosure of that patent is incorporated herein. In this configuration, the first melt passage 88 splits within the melt split bushing 94 and extends to the central melt channel 56 and to the aligned heated nozzle 10.
Extend to four spaced melt bores 68 that extend to an outer annular melt channel 64 of the melt.

An elongated melt transfer bush 96 according to the present invention extends from an aft melt distribution manifold 78 across an adiabatic air space 84 into a bore 98. This bore extends through the front melt distribution manifold 18 and each melt split bush 94. The transfer bush 96 is preferably formed as one part,
In this embodiment, as best seen in FIG. 2, each melt transfer bush 96 has an elongated cylindrical body portion 100 from which a connector bush 102 extends forward. The elongated body portion 100
It has a threaded rear end 104, a front end 106, a central melt bore 108 extending from the rear end 104 to the front end 106, and an integral electrical heating element 110 extending around the central melt bore 108. The threaded rear end of the elongated body portion 100 is mounted on the threaded seat 112 of the rear melt distribution manifold 78. The connector bush 102 also has a threaded rear end 114, a front end 1
16 and a central melt bore 118 through the connector bush. This bore 118 coincides with the central melt bore 108 of the elongated body portion 100 of the melt transfer bush 96. The threaded rear end 114 of the connector bush 102 is threaded into a threaded seat 120 at the front end 106 of the elongated body portion 100, and the front end 116 of the connector bush 102 is
0 is fitted to a suitable receiving seat 121 provided at the rear end 14. Thereby, the melt transfer bush 96
Can be adjusted to the width of the air space 84 between the front melt distribution manifold 18 and the rear melt distribution manifold 78. The diameter of the elongated body portion 100 of the melt transfer bush 96 is sufficiently small compared to the diameter of the bore 96 of the front melt distribution manifold 18 so that the adiabatic air space 124
Formed around.

A second melt passage 126 extends from the second inlet 128. The second passage branches in the rear melt distribution manifold 78 and passes from the rear end 14 of each heated nozzle 10 through aligned melt bores 108, 118 through each melt transfer bush 96. It extends to a aligned melt bore 66 that extends to body channel 62. Heated nozzle 10 for ease of illustration
Although only one is shown, in a typical configuration a large number (eg, 32, 48, or 64) of heated nozzles 10
Are seated in the mold 12 to receive the melt through the two melt passages 88,126. These melt passages have more complex features than those shown.

In use, the injection molding system is assembled as shown in FIG. 1 and a three-layer preform or one barrier layer made of a material such as EVOH or nylon, as described below, is made of PET-type material. Form another product sandwiched between the two resulting layers. Electric power is applied to the heating element 70 in the front melt distribution manifold 18 and the heating element 42 of the heated nozzle 10 to reduce them by about 296.1.
Heat to a temperature of about 565 ° F. Heating element 86 in rear melt distribution manifold 78 and heating element 110 in melt transfer bush 96
To about 204.4 ° C. (about 400 ° C.).
Heat to operating temperature in F). Water is supplied to the cooling conduit 54 to cool the mold 12 and the gate insert 34. The hot, high pressure melt is then injected into the central inlet 90 of the front melt distribution manifold 18 and the second inlet 128 of the rear melt distribution manifold 78 according to a predetermined injection cycle. First, the injection cylinder (not shown)
Inject a pressurized melt, such as polyethylene terephthalate (PET) type material, through a first melt passage 88. The melt passage branches in each melt split bush 94 and extends to the gate 32 through both the central melt channel 56 and the outer annular melt channel 64 of each heated nozzle 10. Small amount of PET in cavity 3
6 and then injected with ethylene vinyl alcohol (EVO
Another pressurized melt, which is a suitable barrier material such as H) or nylon, is co-injected through the second melt passage 126 by another injection cylinder (not shown). A second melt passage 126 extends across the melt transfer bush 96 and each heated nozzle 1 across the adiabatic air space 84.
0 through the inner annular melt channel 62
Extending to When the cavity 36 is substantially full, the barrier material injection pressure is released to stop the barrier material flow, but the PET flow is continued until the cavity 36 is completely filled. The injection pressure of the PET is then released, and after a predetermined cooling period, the mold is opened for removal. After removal, the mold is closed and the cycle is repeated continuously at a frequency determined by the wall thickness and number and size of the cavities 36 and the exact type of material being molded. Thus, as can be seen, the melt transfer bush 96, in addition to transporting the barrier material across the insulated air space 84 between the two manifolds 18, 78, may also be relatively difficult if the barrier material is nylon. The barrier material is thermally separated as it flows through the hot front melt distribution manifold 18 to further control heat.

Referring now to FIG. 3, which shows an injection molding apparatus according to another embodiment of the present invention. Since many of the components of the various embodiments are the same as those described above, some of the common components will not be described again, and some of the components that will be described again will not be described. The same reference numerals as in are attached. In this embodiment, the rear end 104 of the elongated body portion 100 of each melt transfer bush 96 is not threaded. Melt transfer bush 96 is secured to rear melt distribution manifold 78 by screws 130 that extend through holes 132 in flange portion 134 of elongated body portion 100 and into rear melt distribution manifold 78. Otherwise, the structure and use of the melt transfer bush 96 is the same as described above and need not be repeated.

Next, reference is made to FIGS. 4 and 5 showing an injection molding apparatus according to still another embodiment of the present invention. In this embodiment, the central melt bore 136 of each melt transfer bush 96 includes a rear head portion 138 and an elongated stem portion 140 extending forward from the rear head portion 138.
Penetrates. Each melt transfer bush 96
Head portion 138 of the front melt distribution manifold 1
A spacer that forms an adiabatic air space 84 between the rear melt distribution manifold 78 and the rear melt distribution manifold 78 is formed. An elongated stem portion 140 extends forward through a bore 98 in the front melt distribution manifold 18 and contacts the rear end 14 of the aligned heated nozzle 10. The melt transfer bush 96 may be made of one piece, but in the embodiment shown the threaded rear end 142 of the elongated stem portion 140 has the thread of the head portion 138. It is screwed into the seat 144. This allows the elongated stem portion 140 to be made of wear-resistant tool steel and the rear head portion 138 to be made of a titanium alloy having low thermal conductivity. As can be seen, the front surface 148 and rear surface 150 of the rear head portion 138 have a number of concentric surfaces to reduce heat transfer from the front melt distribution manifold 18 to the cold rear melt distribution manifold 78. Groove 14
6 are provided. The elongated stem portion 140 has a small diameter portion 152 extending between two large diameter portions 154 at its ends. This forms an adiabatic air space 124 around the melt transfer bush 96 when the melt transfer bush 96 extends through the bore 98 of the front melt distribution manifold 18.
As described above, this insulated air space 124 thermally isolates the barrier material as it flows through the hot front melt distribution manifold.

Reference is now made to FIGS. 6 to 9, which illustrate an injection molding apparatus according to a different embodiment of the present invention for molding a three-layer preform or other product by simultaneous or coinjection molding. In this embodiment, the apparatus has a valve gate 32 defined by an elongated valve pin 156 extending through a central bore 136 of each melt transfer bush 96 and an aligned central melt channel 56 of each heated nozzle 10. . Each valve pin 156 is
It has a front end 158 and a rear end or head 159. As best seen in FIGS. 8 and 9, each valve pin 156 has four transverse melt bores 16 rearward from its front end 158.
It has a central bore 160 extending to one. The lateral melt bore 161 extends diagonally outward to the outer surface of the valve pin 156. In this embodiment, each valve pin 156 is
The heated nozzle 10 has a reduced diameter portion 163 that fits into the reduced diameter portion 164 of the central melt channel 56. The reduced diameter portion 163 of the valve pin 156 is connected to the central melt channel 56.
Of the valve pin 156, a space 165 is formed around the reduced diameter portion 163 of the valve pin 156. As described below, the elongated valve pin 156
Is reciprocated between three different positions by a hydraulic actuation mechanism 166 according to a predetermined cycle. In this embodiment, each melt transfer bush 96 includes
It further includes a cylindrical neck portion 167 extending rearwardly into the opening 168 of the rear melt distribution manifold 78 and a central bore 136 extending through the neck portion 167.

As can be seen from the figure, in this embodiment,
The insert portion 58 of each heated nozzle 10 forms one annular melt channel 169 extending around the central melt channel 56. Four spaced melt bores 170 extend rearward from the annular melt channel 169 to the rear end 14 of the heated nozzle 10. The first melt passage 88 for PET is split by a melt split bush 94 and extends to four melt bores 170 following the annular melt channel 169 of the heated nozzle 10. A second melt passage 126 for the barrier material branches in the rear melt distribution manifold 78 and passes through an L-shaped passage 172 formed by drilling in the head portion 138 of each melt transfer bush 96 and through the valve pin 156. Extend from a space 165 around the reduced diameter portion 163 of the valve pin 156 to a longitudinal groove 174 formed by machining so as to extend a predetermined distance rearward. In other embodiments, the groove 174 may extend spirally around the valve pin 156, or the valve pin 156 may be small enough to flow barrier material therearound. However, due to the relatively small volume of the barrier material and the low viscosity of the barrier material, it is preferable to flow through the groove 174. The valve pin 156 fits snugly into the central bore 136 of the melt transfer bush 96 sufficiently to prevent the melt from leaking when the elongated valve pin 156 is reciprocated. Each melt transfer bush 96 is held in proper alignment by small dowel pins 176 that extend between the front melt distribution manifold 18. The insert portion 58 of each heated nozzle 10 includes an insulated air extending between the central melt channel 56 and an annular melt channel 169 surrounding the channel to provide some thermal isolation between the channels. It further has a space 178. The perimeter of the central melt channel 56 is further thermally separated by a circle of spaced holes 180 formed by drilling in the rear end 14 of each heated nozzle 10. This, in combination with the adiabatic air space 124 around the stem portion 140 of each melt transfer bush 96, causes the barrier material to flow as it flows through the hot front melt distribution manifold 18 and the heated nozzle 10. Separate thermally continuously. A front portion 148 of the head portion 138 of each melt transfer bush 96 has a head portion 138.
An outer rim 182 is provided which forms an adiabatic air space 184 between the front melt distribution manifold 18 and the front melt distribution manifold 18 to thermally separate the front melt distribution manifold 18 and the rear melt distribution manifold 78. .

The rear end of the valve pin 156, ie, the head 159
Is connected to a front piston 186 seated on a cylinder 188 in the back plate or cylinder plate 24. The actuating mechanism 166 further comprises a rear piston 190, these two pistons 186, 190 being controlled by a controlled hydraulic pressure applied through a duct 192, reciprocating the valve piston 156 between three different positions. Move. For ease of illustration, hydraulic actuation mechanism 1
Although 66 is shown, it is a matter of course that different types of operating mechanisms such as an electro-mechanical mechanism can be used depending on the application.

In use, each valve pin 156
Initially PE through the annular melt channel 169
It is retracted sufficiently large to allow the T to flow to the first partially open position. In this embodiment, the flow of the barrier material is doubly blocked at this central location.
As can be seen in FIG. 8, the lateral melt bore 161 of the valve pin 156 is too far forward to connect to the space 165 around the reduced diameter portion 163 of the valve pin 156. Further, as can be seen in FIG. 6, the longitudinal or spiral groove 174 of the valve pin 156 does not extend rearwardly in this position large enough to connect to the L-shaped passage 172 of the melt transfer bush 96. In other embodiments,
Only one or the other of these barrier material flow blocking methods need be used.

Thereafter, each of the valve pins 156 is further retracted to the second position shown in FIG. In this position, the lateral melt bore 161 of the valve pin 156
Is connected to a space 165 around the reduced diameter portion 163 of each valve pin 156, and a longitudinal groove 174 of the valve pin 156 is connected to an L-shaped passage 172 of the melt transfer bush 96. This allows the barrier material to flow through the melt passage 126 and into the cavity 36. As mentioned above, the bore 160 is centrally located at the front end 158 of the valve pin 156,
The size of the groove 174 and the central bore 160 is relatively small,
The relatively small volume of the barrier material and the relatively low viscosity of the barrier material ensure that the flow of the barrier material forms an even, very thin layer of extremely expensive barrier material. As can be seen in FIG. 9, the barrier material flowing simultaneously with PET
The PET stream is split into two and the two outer PET layers 19
6, a central barrier material layer 194 is formed.

When the cavity 36 is almost full, the front end of each valve member 156 is returned to the first position and the flow of barrier material through the central bore 160 is stopped. PET
Continues to flow through annular melt channel 169 until cavity 36 is completely filled. Next, each valve pin 156 is driven to the third position, that is, the front closed position. In this position, the front end 158 of the valve pin is
2 and flush with the cavity 36. After a short cooling period, the mold is opened for removal. After removal, the mold is closed and the wall thickness of the cavity 36,
The cycle is repeated continuously every 15 to 30 seconds at a frequency determined by the number, size, and exact material being molded.

Next, reference is made to FIG. 10 showing an injection molding apparatus according to another embodiment of the present invention. Also in this embodiment, each melt transfer bush 96 has a central bore 1 extending through an elongated stem portion 140 and a rear head portion 138.
36. The rear head portion 138 forms a spacer between the two melt distribution manifolds 18,78. An elongated pin 198 is attached to the rear surface 202 of the head portion 138 of each melt transfer bush 96 with its head 200.
And has a partially tapered front end 204 adjacent to and aligned with one gate 32 and secured in place. Although not shown in FIG. 10 due to the size of the drawing, the elongated pin has a central bore 160 extending to its front end 204, as shown in FIG.
, A lateral bore 161 is provided. During each cycle, the PET is first injected through the first melt passage 88. PET flows through the annular melt channel 168 of each heated nozzle 10 to the gate 32 following the cavity 36. A short time after the start of PET injection, a predetermined amount of low-viscosity barrier material is simultaneously injected through the second melt passage 126. This forms a central barrier material layer 194 between the two outer PET layers 196. When the cavity 36 is substantially full, the injection pressure of the barrier material is released and its flow is stopped. The injection of PET is continued until the cavity 36 is completely filled. The injection pressure of PET is then released, and after a short cooling period, the mold is opened for removal. After removal, the mold 12 is closed and the wall thickness of the cavity 36,
The cycle is repeated continuously every 15 to 30 seconds at a frequency determined by the number, size, and exact material being molded.

An injection molding apparatus in which a melt transfer bush traverses an air space 84 between the front melt distribution manifold 18 and the rear melt distribution manifold 78 has been described with respect to some embodiments, but is claimed below. It will be appreciated by those skilled in the art that various other embodiments are possible without departing from the scope of the present invention described in. For example, the present invention has been described with respect to an injection molding apparatus for three-layer molding, but the present invention can also be used for an injection molding apparatus for five-layer molding.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a part of a multilayer injection molding apparatus having a melt transfer bush according to an embodiment of the present invention.

FIG. 2 is a perspective view of one melt transfer bush shown in FIG.

FIG. 3 is a sectional view showing a melt transfer bush according to another embodiment of the present invention.

FIG. 4 is a partial cross-sectional view of a portion of a multilayer injection molding apparatus having a melt transfer bush according to another embodiment of the present invention.

FIG. 5 is a perspective view of the melt transfer bush shown in FIG. 4;

FIG. 6 is a partial cross-sectional view of a part of a valve gate type multilayer injection molding apparatus having a melt transfer bush according to still another embodiment of the present invention.

FIG. 7 is a perspective view of the melt transfer bush shown in FIG. 6;

FIG. 8 is an enlarged sectional view showing the valve pin of FIG. 6 in a partially open position.

FIG. 9 is an enlarged sectional view showing the valve pin in a fully open position.

FIG. 10 is a partial cross-sectional view of a part of a multilayer injection molding apparatus having a melt transfer bush according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Heated nozzle 12 Mold 14 Rear end 16 Front surface 18 Front melt distribution manifold 20 Heated nozzle retainer plate 22 Manifold retainer plate 24 Back plate 28 Cavity retainer plate 30 Front end 32 Gate 34 Cooled gate insert 36 Cavity 38 Cavity insert Body 40 Mold core 56 Central melt channel 62, 64 Annular melt channel 78 Rear melt distribution manifold 84 Air space 96 Melt transfer bush 124 Air space 136 Central melt bore 138 Head portion 140 Stem portion

Claims (24)

[Claims] 1. A multi-cavity hot runner injection molding apparatus for multi-layer molding, comprising: a front melt distribution manifold attached to a mold and a rear side extending substantially parallel to each other with an adiabatic air space therebetween. A melt distribution manifold; a rear end, a front end, a central melt channel penetrating from the rear end to the front end, an inner annular melt channel extending around the central melt channel to the front end,
A first melt bore extending from the rear end to the inner annular melt channel; and an outer annular melt channel extending around the central melt channel and the inner annular melt channel to the front end. And a plurality of heated nozzles having at least one second melt bore having an outer annular melt channel extending from the rear end to the outer annular melt channel, wherein the heated nozzle comprises the heated nozzle. The rear end of each of the nozzles is mounted to the mold with the front melt distribution manifold in contact with the front melt distribution manifold, and a first melt passage from a first melt source is located within the front melt distribution manifold. At the center melt channel and from the rear end of the heated nozzle to the outer annular melt channel. Extending through the at least one second melt bore extending and the outer annular melt channel of each of the heated nozzles to a gate adjacent a front end of the heated nozzle following the mold cavity; A second melt passage from a second melt source branches in the rear melt distribution manifold and passes through the inner melt channel of each of the first melt bore and the heated nozzle. An injection molding device, extending to the gate, having a plurality of melt transfer bushes, each of which has a rear end, a front end, and a central melt bore penetrating from the rear end to the front end. , Each of the melt transfer bushes is separated from the rear melt distribution manifold by the rear melt distribution manifold and the front melt distribution manifold. The front melt distribution across the adiabatic air space between the manifold and the first melt bore extending from the rear end of one of the heated nozzles to the inner annular melt channel; Extending in a bore through the manifold, whereby the central bore through each of the melt transfer bushes forms part of the second melt passage;
An injection molding apparatus characterized by the above-mentioned. 2. Each of said melt transfer bushes extends through a bore through said front melt distribution manifold and is in sealing contact with the rear end of said one of said heated nozzles. The injection molding apparatus according to claim 1. 3. The injection molding apparatus according to claim 2, wherein there is an adiabatic air gap between each of said melt transfer bushes and said front melt distribution manifold surrounding said melt transfer bush. 4. Each of the melt transfer bushes has an integral electric heating element extending around at least a portion of the central melt bore through the melt transfer bush. The injection molding device according to claim 3, wherein the injection molding device has a spiral portion. 5. Each of the melt transfer bushes includes an elongated body and a connector bush, the elongated body having a rear end, a front end, and a central melt bore extending from the rear end to the front end. Wherein the connector bush has a rear end, a front end, and a central melt bore extending through the connector bush, the central melt bore being aligned with the central melt bore extending through the elongated body portion; The injection molding apparatus according to claim 2, wherein the connector bush extends forward from the elongated body portion. 6. The rear end of each of the elongated body portions of the melt transfer bushing includes a seat having a thread extending around the second melt passage of the rear melt distribution manifold. 6. The injection molding device according to claim 5, wherein a screw thread is provided for screwing. 7. One of the central melt bores at the front end of each of the elongated body portions of the melt transfer bush and the first melt bore extending from the rear end of the aligned heated nozzle. An end of the connector bush having a thread provided on one of the front end or the rear end thereof, and a thread provided on one of the front end and the rear end of the connector bush; A thread of one of the central melt bore provided at the front end of each elongated body portion of each of the melt transfer bushes and the first melt bore extending from the rear end of the heated nozzle. Screwed into a seat with
The injection molding apparatus according to claim 6. 8. Each of said melt transfer bushes has a head portion and an elongated stem portion, said head portion extending between said rear melt distribution manifold and said front melt distribution manifold. The elongated stem portion extends forward from the head portion and through the bore through the front melt distribution manifold, the spacer portion extending as a spacer forming an adiabatic air space between the manifolds. The injection molding apparatus according to the above. 9. A multi-cavity hot runner injection molding apparatus for multilayer molding, comprising: a front melt distribution manifold attached to a mold and a rear side extending substantially parallel to each other with an adiabatic air space therebetween. A melt distribution manifold; a rear end, a front end, a central melt channel penetrating from the rear end to the front end, and an annular melt channel extending around the central melt channel to the front end,
A plurality of heated nozzles having at least one melt bore having an annular melt channel extending from the rear end of the heated nozzle to the annular melt channel, wherein the heated nozzle comprises a nozzle of the heated nozzle; Each of the rear ends is attached to the mold with the front melt distribution manifold abutting thereon, and a first melt passage from a first melt source branches within the front melt distribution manifold. Extending through the at least one melt bore and the annular melt channel of each of the heated nozzles to a gate adjacent the front end of the heated nozzle following the cavity of the mold; A second melt passage from the second melt source branches in the rear melt distribution manifold, and the central melt channel of each of the heated nozzles. An injection molding device extending through the tunnel to the gate, a head portion provided at the rear end, an elongated stem portion extending forward from the head portion to the front end, and a central bore extending from the rear end to the front end. A plurality of melt transfer bushes, each of the melt transfer bushes being mounted in alignment with the central melt channel of one of the heated nozzles, wherein the head portion includes Between the side melt distribution manifold and the front melt distribution manifold,
Extending as a spacer forming an adiabatic air space between the manifolds, the elongated stem portion passes from the head portion forward through aligned heated nozzles into a bore through the front melt distribution manifold. The central bore extends through each of the melt transfer bushes in alignment with the central melt channel such that the central bore extends forwardly from the bore into the central melt channel in the aligned heated nozzle. An elongated pin extending from the second melt source, the second melt passage extending from the second melt source extending along the elongated pin. 10. The melt transfer bush, wherein said elongated stem portion extends through a bore through said front melt distribution manifold, and wherein said front end of each of said melt transfer bushes is connected to said aligned cover. The injection molding apparatus according to claim 9, wherein the apparatus is in contact with the rear end of the heating nozzle. 11. The injection molding apparatus according to claim 10, wherein there is an adiabatic air gap between said elongated stem portion of each of said melt transfer bushes and said surrounding melt distribution manifold. 12. The head portion of each of the melt transfer bushes extends from an inlet provided at the rear end to join the central melt channel and form a portion of the second melt passage. The injection molding apparatus according to claim 11, having an off-center melt channel. 13. The off-center melt channel may be L
13. The injection molding device according to claim 12, wherein the injection molding device is shaped like a letter. 14. The injection molding apparatus according to claim 12, wherein said elongated pin is a valve pin, and further comprising an operating mechanism for reciprocating said valve member between a retracted open position and a front closed position. 15. Each of the melt transfer bushes further includes a neck portion extending rearward from the head portion into an opening of the rear melt distribution manifold.
15. The injection of claim 14, wherein the elongate valve pin fits snugly in the central bore of the neck portion to prevent leakage of melt as the elongate valve pin reciprocates. Molding equipment. 16. The injection molding apparatus according to claim 12, wherein said elongated pin is a fixed pin provided with a melt groove extending in a longitudinal direction. 17. The injection molding apparatus according to claim 1, wherein there is an adiabatic air space between each of said heated nozzles and a mold surrounding said nozzles. 18. The method of claim 1, wherein the adiabatic air space between the rear melt distribution manifold and the front melt distribution manifold is formed by placing a plurality of spacers between the manifolds. The injection molding apparatus according to the above. 19. An adiabatic air space between the front melt distribution manifold and the mold to be cooled surrounding the manifold.
The injection molding apparatus according to claim 1. 20. The adiabatic air space between the front melt distribution manifold and the surrounding mold to be cooled as defined by the arrangement of a central locating ring therebetween. Injection molding equipment. 21. The injection molding apparatus according to claim 1, wherein there is an adiabatic air space between said rear melt distribution manifold and a back plate. 22. The injection molding apparatus according to claim 19, wherein there is an adiabatic air space between said rear melt distribution manifold and a back plate. 23. The injection molding apparatus according to claim 22, wherein there is an adiabatic air space between each of said heated nozzles and a mold surrounding said nozzles. 24. The adiabatic air space is provided between a first melt passing through the rear melt distribution manifold and a second melt passing through the front distribution manifold. The injection molding apparatus according to claim 1, which provides sufficient thermal separation on entry to maintain a predetermined temperature difference.